// SPDX-License-Identifier: GPL-2.0+
/*
 * 8250_dma.c - DMA Engine API support for 8250.c
 *
 * Copyright (C) 2013 Intel Corporation
 */
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_reg.h>
#include <linux/dma-mapping.h>

#include "8250.h"

#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
#define MAX_TX_BYTES 64
#define MAX_FIFO_SIZE 64
#define UART_RFL_16550A 0x21
#endif

static void _dma_tx_complete(void *param)
{
    struct uart_8250_port *p = param;
    struct uart_8250_dma *dma = p->dma;
    struct circ_buf *xmit = &p->port.state->xmit;
    unsigned long flags;
    int ret;

    dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr, UART_XMIT_SIZE, DMA_TO_DEVICE);

    spin_lock_irqsave(&p->port.lock, flags);

    dma->tx_running = 0;

    xmit->tail += dma->tx_size;
    xmit->tail &= UART_XMIT_SIZE - 1;
    p->port.icount.tx += dma->tx_size;

    if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) {
        uart_write_wakeup(&p->port);
    }

    ret = serial8250_tx_dma(p);
    if (ret) {
        serial8250_set_THRI(p);
    }

    spin_unlock_irqrestore(&p->port.lock, flags);
}

#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)

static void _dma_rx_complete(void *param)
{
    struct uart_8250_port *p = param;
    struct uart_8250_dma *dma = p->dma;
    struct tty_port *tty_port = &p->port.state->port;
    struct dma_tx_state state;
    unsigned int count = 0, cur_index = 0;

    dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
    cur_index = dma->rx_size - state.residue;

    if (cur_index == dma->rx_index) {
        return;
    } else if (cur_index > dma->rx_index) {
        count = cur_index - dma->rx_index;
    } else {
        count = dma->rx_size - dma->rx_index;
    }

    tty_insert_flip_string(tty_port, dma->rx_buf + dma->rx_index, count);

    if (cur_index < dma->rx_index) {
        tty_insert_flip_string(tty_port, dma->rx_buf, cur_index);
        count += cur_index;
    }

    p->port.icount.rx += count;
    dma->rx_index = cur_index;
}

#else

static void _dma_rx_complete(void *param)
{
    struct uart_8250_port *p = param;
    struct uart_8250_dma *dma = p->dma;
    struct tty_port *tty_port = &p->port.state->port;
    struct dma_tx_state state;
    int count;

    dma->rx_running = 0;
    dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);

    count = dma->rx_size - state.residue;

    tty_insert_flip_string(tty_port, dma->rx_buf, count);
    p->port.icount.rx += count;

    tty_flip_buffer_push(tty_port);
}

#endif

int serial8250_tx_dma(struct uart_8250_port *p)
{
    struct uart_8250_dma *dma = p->dma;
    struct circ_buf *xmit = &p->port.state->xmit;
    struct dma_async_tx_descriptor *desc;
    struct uart_port *up = &p->port;
    int ret;

    if (dma->tx_running) {
        if (up->x_char) {
            dmaengine_pause(dma->txchan);
            uart_xchar_out(up, UART_TX);
            dmaengine_resume(dma->txchan);
        }
        return 0;
    } else if (up->x_char) {
        uart_xchar_out(up, UART_TX);
    }

    if (uart_tx_stopped(&p->port) || uart_circ_empty(xmit)) {
        /* We have been called from _dma_tx_complete() */
        serial8250_rpm_put_tx(p);
        return 0;
    }

    dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
    if (dma->tx_size < MAX_TX_BYTES) {
        ret = -EBUSY;
        goto err;
    }
#endif
    desc = dmaengine_prep_slave_single(dma->txchan, dma->tx_addr + xmit->tail, dma->tx_size, DMA_MEM_TO_DEV,
                                       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
    if (!desc) {
        ret = -EBUSY;
        goto err;
    }

    dma->tx_running = 1;
    desc->callback = _dma_tx_complete;
    desc->callback_param = p;

    dma->tx_cookie = dmaengine_submit(desc);

    dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr, UART_XMIT_SIZE, DMA_TO_DEVICE);

    dma_async_issue_pending(dma->txchan);
    if (dma->tx_err) {
        dma->tx_err = 0;
        serial8250_clear_THRI(p);
    }
    return 0;
err:
    dma->tx_err = 1;
    return ret;
}

#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)

int serial8250_rx_dma(struct uart_8250_port *p)
{
    unsigned int rfl, i = 0, fcr = 0, cur_index = 0;
    unsigned char buf[MAX_FIFO_SIZE];
    struct uart_port *port = &p->port;
    struct tty_port *tty_port = &p->port.state->port;
    struct dma_tx_state state;
    struct uart_8250_dma *dma = p->dma;

    fcr = UART_FCR_ENABLE_FIFO | UART_FCR_T_TRIG_10 | UART_FCR_R_TRIG_11;
    serial_port_out(port, UART_FCR, fcr);

    do {
        dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
        cur_index = dma->rx_size - state.residue;
    } while (cur_index % dma->rxconf.src_maxburst);

    rfl = serial_port_in(port, UART_RFL_16550A);
    while (i < rfl) {
        buf[i++] = serial_port_in(port, UART_RX);
    }

    _dma_rx_complete(p);

    tty_insert_flip_string(tty_port, buf, i);
    p->port.icount.rx += i;
    tty_flip_buffer_push(tty_port);

    if (fcr) {
        serial_port_out(port, UART_FCR, p->fcr);
    }
    return 0;
}

int serial8250_start_rx_dma(struct uart_8250_port *p)
{
    struct uart_8250_dma *dma = p->dma;
    struct dma_async_tx_descriptor *desc;

    desc = dmaengine_prep_dma_cyclic(dma->rxchan, dma->rx_addr, dma->rx_size, dma->rx_size, DMA_DEV_TO_MEM,
                                     DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
    if (!desc) {
        return -EBUSY;
    }

    dma->rx_running = 1;
    desc->callback = NULL;
    desc->callback_param = NULL;

    dma->rx_cookie = dmaengine_submit(desc);
    dma_async_issue_pending(dma->rxchan);
    dma->rx_index = 0;
    return 0;
}

#else

int serial8250_rx_dma(struct uart_8250_port *p)
{
    struct uart_8250_dma *dma = p->dma;
    struct dma_async_tx_descriptor *desc;

    if (dma->rx_running) {
        return 0;
    }

    desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr, dma->rx_size, DMA_DEV_TO_MEM,
                                       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
    if (!desc) {
        return -EBUSY;
    }

    dma->rx_running = 1;
    desc->callback = _dma_rx_complete;
    desc->callback_param = p;

    dma->rx_cookie = dmaengine_submit(desc);

    dma_async_issue_pending(dma->rxchan);

    return 0;
}

#endif

void serial8250_rx_dma_flush(struct uart_8250_port *p)
{
    struct uart_8250_dma *dma = p->dma;

    if (dma->rx_running) {
        dmaengine_pause(dma->rxchan);
        _dma_rx_complete(p);
        dmaengine_terminate_async(dma->rxchan);
    }
}
EXPORT_SYMBOL_GPL(serial8250_rx_dma_flush);

int serial8250_request_dma(struct uart_8250_port *p)
{
    struct uart_8250_dma *dma = p->dma;
    phys_addr_t rx_dma_addr = dma->rx_dma_addr ? dma->rx_dma_addr : p->port.mapbase;
    phys_addr_t tx_dma_addr = dma->tx_dma_addr ? dma->tx_dma_addr : p->port.mapbase;
    dma_cap_mask_t mask;
    struct dma_slave_caps caps;
    int ret;

    /* Default slave configuration parameters */
    dma->rxconf.direction = DMA_DEV_TO_MEM;
    dma->rxconf.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
    dma->rxconf.src_addr = rx_dma_addr + UART_RX;
#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
    if ((p->port.fifosize / 0x4) < 0x10) {
        dma->rxconf.src_maxburst = p->port.fifosize / 0x4;
    } else {
        dma->rxconf.src_maxburst = 0x10;
    }
#endif

    dma->txconf.direction = DMA_MEM_TO_DEV;
    dma->txconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
    dma->txconf.dst_addr = tx_dma_addr + UART_TX;
#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
    dma->txconf.dst_maxburst = 0x10;
#endif
    dma_cap_zero(mask);
    dma_cap_set(DMA_SLAVE, mask);

    /* Get a channel for RX */
    dma->rxchan = dma_request_slave_channel_compat(mask, dma->fn, dma->rx_param, p->port.dev, "rx");
    if (!dma->rxchan) {
        return -ENODEV;
    }

    /* 8250 rx dma requires dmaengine driver to support pause/terminate */
    ret = dma_get_slave_caps(dma->rxchan, &caps);
    if (ret) {
        goto release_rx;
    }
    if (!caps.cmd_pause || !caps.cmd_terminate || caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR) {
        ret = -EINVAL;
        goto release_rx;
    }

    dmaengine_slave_config(dma->rxchan, &dma->rxconf);

    /* RX buffer */
#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
    if (!dma->rx_size) {
        dma->rx_size = PAGE_SIZE * 0x2;
    }
#else
    if (!dma->rx_size) {
        dma->rx_size = PAGE_SIZE;
    }
#endif

    dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size, &dma->rx_addr, GFP_KERNEL);
    if (!dma->rx_buf) {
        ret = -ENOMEM;
        goto release_rx;
    }

    /* Get a channel for TX */
    dma->txchan = dma_request_slave_channel_compat(mask, dma->fn, dma->tx_param, p->port.dev, "tx");
    if (dma->txchan) {
        dmaengine_slave_config(dma->txchan, &dma->txconf);

        /* TX buffer */
        dma->tx_addr = dma_map_single(dma->txchan->device->dev, p->port.state->xmit.buf, UART_XMIT_SIZE, DMA_TO_DEVICE);
        if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
            dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf, dma->rx_addr);
            dma_release_channel(dma->txchan);
            dma->txchan = NULL;
        }

        dev_info_ratelimited(p->port.dev, "got rx and tx dma channels\n");
    } else {
        dev_info_ratelimited(p->port.dev, "got rx dma channels only\n");
    }

#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
    /* start dma for rx */
    serial8250_start_rx_dma(p);
#endif
    return 0;
release_rx:
    dma_release_channel(dma->rxchan);
    return ret;
}
EXPORT_SYMBOL_GPL(serial8250_request_dma);

void serial8250_release_dma(struct uart_8250_port *p)
{
    struct uart_8250_dma *dma = p->dma;

    if (!dma) {
        return;
    }

    /* Release RX resources */
    dmaengine_terminate_sync(dma->rxchan);
    dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf, dma->rx_addr);
    dma_release_channel(dma->rxchan);
    dma->rxchan = NULL;
#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
    dma->rx_running = 0;
#endif
    /* Release TX resources */
    if (dma->txchan) {
        dmaengine_terminate_all(dma->txchan);
        dma_unmap_single(dma->txchan->device->dev, dma->tx_addr, UART_XMIT_SIZE, DMA_TO_DEVICE);
        dma_release_channel(dma->txchan);
        dma->txchan = NULL;
        dma->tx_running = 0;
    }
    dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
}
EXPORT_SYMBOL_GPL(serial8250_release_dma);
